Megadream 300FT Professional Wireless Digital Swimming Pool SPA Floating Thermometer Transmitter with Indoor Temperature, Back Light,Date and Alarm Function An easy way to read your water temperature from both indoors and outdoors The screw-on lid design with internal gasket provides a leak free, water resistant design The wireless pool and spa thermometer is water proof and floats on the surface of the water. The sensor displays and wirelessly transmits the water temperature to the display console In normal clock mode, LCD displays indoor temperature, water temperature,month,date,week,hour,minute,second,and reception channel After batteries are inserted it starts to sense water temperature and transmit temperature data to main station. Red LED flashes while transmission is proceeding